Airplane stabilizer



July 16, 1935. c, J CRANE 2,007,964

AIRPLANE STABILIZ-ER Filed Feb. 15, 1933 2 Sheets-Sheet 1 (tar [CraneJuly 16, 1935. I c. J. CRANE 2,007,964

AIRPLANE STABILIZER Filed Feb. is, 1933 2 Sheets-Sheet 2 C r rarze AxiomPatented July 16, 1935 UNITED STATES PAT-E TIOFFICE- 2,007,964 AIRPLANESTABILIZER- 1 7 Carl J. Crane, Albrook Field, Canal Zone ApplicationFebruary 15, .1933, Serial No. 656.861

3 Claims. (01. era-29) (Granted under the act of March 3, 1 883, asamended April 30, 1928; 370 0. G. 757) bilizer for airplanes whichdepends for its operation on changes in the normal directional flow ofair past the airplane while in flight.

A further object is to provide a stabilizer of the type stated abovewhich may be applied to all standard forms of airplanes, withoutalteration of the controls.

Briefly stated, the stabilizer which forms the subject matter of thisinvention consists of slip rotatably mounted upon the 'wingandoperatively connected to the ailerons for the purpose of trimming thelateral spread of the wings through the action of said ailerons.

It is well known that in the conventional airplane control system thereare three principal controlling surfaces, namely; the rudder, theailerons and the elevators. It is also well known that in making a turnallthree of the controlling surfaces may be called into play. The usualcontrol surfaces to be moved in executing a turn are the rudder andailerons. The airplane must be banked at the same time that it is turnedin order to prevent a slip or skid. This control coordination is usuallybrought about by the pilot in handling the aileron and the ruddercontrols in such a manner that the slip and/or skid willbe prevented.

It is also a well known fact that certain types of airplanes aresomewhat unstable laterally during straight flight. This lack of lateralstability during straight flight requires constant attention of thepilot as he must, by'means of the'ailerons, keep the wing levellaterally. It is to correct this unstable condition and to avoid lateralskidding or slipping without necessitating the operation of the controlsby the pilot, that the automatic control, which forms the subject'matterof this invention, was devised.

The device set forth by this invention is especially useful during blindflight such as in a fog or other conditions of darkness that preventoutside visual reference. It is then that the pilot desires to simplifyhis control movement to a minimum. It will be noted that with this typeof control it is only necessary to steer with the rudder, sincethe..resultant skid will produce the necessary movement or the aileronsto bring about a coordinated air position "of the airplane- In stoppingthe turnby theruddei' alone the resulting slip will raise the lowportion of the wing through the interrelation of the slip fin and theaileron. The pilot will not have to use the alleron control mountedwithin the airplane, the

rudder sufilcing to bring about the coordinated turning flight orlaterally trimmed straight In order that theinvention may be morereadily understood, reference is bad to the accompanying drawingsforming a part of this specification:

Fig. 1 is a top plan View of an airplane showing the relative positionsof the ailerons with respect to the stabilizing fins; j Fig. 2 is afront elevation of an airplane pictured in a right hand slip, andshowing the position in which the fins are yawed and the correspondingposition of the ailerons;

Fig. 3 is a perspective view showing a slip fin and aileron and thelinkage connecting the two. It alsoshows a portion of the linkagebetween the aileron and the control stick; 7

Fig. 4; is a side elevation partially in section of a plane with aileronhingably attached thereto, a sli fin and linkage between said fin andsaid aileron;

Figi 5 is a partial top plan view of the structure shown in Figure 1with a portion of the covering of the plane tornaway to show the linkageof the fin to the aileron;

6 is a similar view of Fig. 4 showing a modified form of linkage betweenthe fin and the aileron; f

Fig. 7 is a sectional view taken along the line 1 of Fig. 6 showing aportion of the linkage between the fin, aileron and the control stick,and

Fig. 8 is a top plan View of a portion of a plane and aileron, with asection of the plane covering torn away to expose the modified form oflinkage shown in Figs. 6 and 7.

Referring to the drawings, the numeral (I) represents the fuselage of anairplane, (2) the wing, (3) and (3) the right and left ailerons, and (4)and (4) the right and left slip fins. The relative positionment of theailerons and fins are shown in Fig. 1. The slip fins (4) and (4) arepivotally mounted on perpendicular shafts (5) and (5') above the planesand are so linked to the ailerons'that when they are turned rightaileron (3) is turned downward and the left aileron (4') is turnedupward as is shown in Fig. 2. When the slip fins (4) and (4') are turnedin the direction indicated by (4b) and (4'17), the right aileron (3) isturned upward and the left aileron (3) is turned downward.

In Fig. 2 the airplane is pictured flying in a right hand slip. The slipfins (4) and (4) are yawed in a manner which will cause the rightaileron (3) to be lowered and. the left aileron (3') to be raised whichwill correct for the slip. The direction of the wind resistance and thedirection of slip of the airplane are indicated by the arrows shown inthis illustration.

A type of linkage between a slip fin and aileron is shown in Fig. 3. Inthis illustration which shows the right aileron (3) and slip fin (4), itwill be noted that the slip fin (4) is rigidly mounted on a revolvableshaft (5) having attached thereto a cross member (6). At either end ofthis cross member (6) are fastened the springs ('I) and (8), whichconnect with the cables'(9) and (Ill). These cables (9) and (ID) are inturn attached to the upper and lower horns (II) and (I2) which aremounted respectively on the upper and lower surfaces of the aileron (3).

The horn (I3) mounted on the lower surface of the aileron (3) ispivotally attached to link (I4) which in turn is pivoted to a disc (I5).The disc (I5) is rotated by the control stick (not shown) through theinstrumentality of a connecting linkage, a portion of which is indicatedby the nu meral (I6).

Figs. 4 and 5 show other views of the linkage between the slip fin (4)and the aileron (3) It will be noted that in this linkage there isincluded an elastic system, the purpose of which is toallow a damping ofthe relative movements-of the aileron and the slip fin, and also toprevent a too rigid control of the lateral movement of the wings and todamp out the effects of gusts from the side.

Figs. 6, '7, and 8 show another method of interconnecting the slip fin(4) and the aileron (3). In this type of linkage the rotatable shaft(5), to which the fin (4) is rigidly attached, is provided with abell-crank (I'I), connected to the horn (II) of the aileron (3) throughthe link I8) and the longitudinally slidable rod I9), all of which arepivotally connected to each other. The bell crank (I1) is connected tothe control lever (not shown) by means of the link (28) and rod (2|). Inthis type of linkage no elastic system is provided, and but a singlelinkage is required for both elevating and lowering the aileron.

The sizes and shapes of the fins and methods of mechanically linking theslip fins with the ailerons may be varied to include a large number ofcombinations. It should be noted-that the position of the slip fin mayvary from the posiin the direction indicated by (40.) and (4a) the tionshown in the drawings. The fin may be above or below the individual wingor wings of monoplane or biplane respectively.

It is obvious that those skilled in the art may vary the details ofconstruction and arrangement of parts without departing from the scopeand spirit of the invention, and therefore it is not desired to belimited to the foregoing description except as may be required by theclaims.

Having described my invention, what I claim as new and wish to secure byLetters Patent is:

1. In an airplane having a wing with manually controlled ailerons, hornsprojecting from the upper and lower surfaces of said ailerons,vertically rotatable shafts mounted within said Wing and projectingabove the same, rotating means comprising horizontal cross membersrigidly attached to the portion of said shafts located within said wing,air engaging elements comprising slip fins rigidly attached to the upperportion of said shafts, tension linkage elements comprising a cable andspring, uniting said cross members with said horns for coordinating themovements of said ailerons with those of the slip fins and additionallinkage for operatively connecting the ailerons with the manual controldevice.

2. In an airplane having a wing with manually controlled ailerons, hornsprojecting from the upper and lower surfaces of said ailerons, verticalrotatable shafts mounted within said wing and i projecting above thesame, rotating means comprising horizontal cross members rigidlyattached to the portion of said shafts located within said wing, airengaging elements comprising slip fins rigidly attached to the upperportion of said rotary movement about their vertical axes, and

additional linkage for operatively connecting the ailerons with themanual control device.

3. In an airplane having a wing with manually controlled aileronslocated at its rearward lateral extremity, horns projecting from theupper and lower surfaces of said ailerons, vertical rotatable shaftsmounted within said wing and projecting above the same in advance ofsaid ailerons, rotating means comprising horizontal cross membersrigidly attached to the portion of said shafts located within said wing,air engaging elements comprising slip fins rigidly attached to the upperportion of saidshafts, tension linkage elements comprising a cable andspring, uniting said cross members with said horns for coordinating themovements of said ailerons with those of the slip fins, and additionallinkage for operatively con necting the ailerons with the manual controldevice.

CARL J. CRANE.

